Italy became the latest national football federation to distance itself from Infantino, while European Leagues President Claudius Schaefer told The Athletic that the FIFA chief had no future at the organisation and that world football's governing body needed reform.
The move follows FIFA's decision in July to withdraw a proposal that triggered opposition from UEFA's 55 member associations, which agreed to boycott FIFA competitions after details of the plan emerged last month.
UEFA's potential boycott has been brought into sharper focus with teams currently preparing for the Under-20 Women's World Cup in Poland, which is due to begin on September 5th.
UEFA officials are expected to tell the governing body's executive committee and the presidents of most of its member associations at a meeting in Monaco on Thursday that the conditions for lifting the boycott have been met, the sources said.
UEFA has sought both the withdrawal of the proposal and assurances that similar plans would not be pursued again.
"It's not a UEFA defeat, rather the reality of avoiding hurting young players' once in a lifetime opportunity. The actions and insistence on change will continue," a source familiar with the discussions told Reuters.
Italy withdraws support for Infantino
The Italian Football Federation (FIGC) withdrew its support for Infantino's candidacy in the FIFA presidential election scheduled for March next year.
"This decision is intended to clearly and transparently express the FIGC's position - in full agreement with UEFA and its president Aleksander Ceferin - regarding the recent initiatives promoted by the FIFA president concerning the governance and development of international competitions," FIGC said in a statement.
Pressure on Infantino has continued to mount.
He is under pressure from three confederations to resign, including UEFA, the Asian Football Confederation and CONCACAF, which represents North and Central America and the Caribbean.
The regional governing bodies have discussed a potential vote of no confidence in Infantino, who is planning to seek re-election for a fourth term next year and is likely to face strong opposition.
Infantino, who retains support from the African and South American confederations, has sought to sideline the confederations and appeal directly to individual members.